Table 3

Safety in pregnancy of selected antimicrobial agents commonly used to treat pneumonias

Class of antibiotic Evidence regarding adverse effects Safety in human pregnancy
Antibacterial agents
Penicillins Widely used without evidence of problemsGood
Cephalosporins Widely used without evidence of problemsGood
Macrolides Widely used without evidence of problems. Most information relates to erythromycin and less to clarithromycin or azithromycinGood
AminoglycosidesNo published reports on fetal nephropathy after maternal gentamicin, however ability of premature infants to eliminate gentamicin seems to be dependent on gestational age91 Potential risk of nephropathy and ototoxicity. Maternal plasma levels should be carefully monitored if clear indication exists for its use
Sulphonamides May cause kernicterus if given in late pregnancy. Of 2296 newborns exposed to co-trimoxazole during the first trimester, 126 (5.5%) major birth defects were observed, 98 expected92 Avoid. Insufficient information on high doses. Theoretical risk of neural tube defects with co-trimoxazole due to its folate antagonist activity
Quinolones Arthralgia and tendonitis reported in adults but none following in utero exposure in human pregnancy91 Insufficient evidence of safety
TetracyclinesAdministration in the second or third trimesters can cause yellow-brown staining and banding of the teeth of the child and reversible growth retardation of the long bones91 Avoid, especially at or after 12 weeks
MetronidazoleConflicting data. Some epidemiological studies suggest increased risk of malformations, stillbirths and low birth weight infants. Other studies totalling exposure to over 3000 newborns have found no increase in congenital anomalies91 Unclear
Antiviral agents
AmantadineLimited preclinical data in animals showed a possible association with cleft palate. In a study of 64 pregnancies five births with defects were reported93 Insufficient evidence of safety
ZanamivirNo information in humans. In animals high doses were not associated with malformation (GlaxoWellcome Summary of Product Characteristics, Relenza, 2000)Insufficient evidence of safety. Theoretically safer than amantadine
Ribavirin Teratogenic or embryolethal in nearly all animal speciesAvoid
AciclovirProspective register (1984–99) with data on 1246 pregnancies showed no increase in birth defects compared with the general population (GlaxoWellcome Medical Information, personal communication)Use recommended in situations where risk from untreated infection is greater than risk of possible adverse effects e.g. life threatening varicella infections
Antifungal agents
Amphotericin B Case reports of fetal toxicity involving anaemia, transient acidosis with uraemia, and respiratory failure94 Use if benefit outweighs risk of fetal toxicity (usually maternal toxicity also present)
ItraconazoleEmbryotoxic and teratogenic in laboratory animals.95 Of 198 women exposed during the first trimester, 3.2% major malformations were seen95 Best avoided. Manufacturer recommends contraception during and for one menstrual cycle after stopping treatment
FluconazoleEmbryotoxic and teratogenic in high doses in rats. Multiple congenital abnormalities reported with high dose use in humans. Possible dose dependent teratogenicity94 Avoid